1. Field of the Invention
The invention is in the general area of home uterine activity monitoring devices and methods.
2. Description of the Related Art
Human pregnancy should ideally last about 38 weeks from conception. However often it does not and infants born before about 37 weeks of gestation are at high risk for medical complications and mortality. The care and treatment of these premature infants imposes enormous costs upon the medical system. Indeed the treatment of extremely low birth weight infants can occasionally result in over a million dollars of medical costs for each infant.
In addition to the trauma, suffering, and financial distress that such premature births place on the infant's family, surviving premature infants are at increased risk for lifelong problems, including cerebral palsy, vision loss, hearing loss, and mental retardation.
In order to help prevent premature births, it can be important to monitor the uterus for abnormal contractions and other signs of preterm labor. If such abnormal contractions and other signs of preterm labor can be detected in time, various anti-contraction medications, called tocolytic agents may be administered to slow down or stop preterm labor. These tocolytic drugs include Terbutaline, Ritodrine, Nifedipine, and others. Although many of these drugs may only delay subsequent labor by a number of days, this extra time can make all the difference for preterm infant survival. Premature infant lungs are often not capable of functioning properly in an air environment, but if the physician knows in advance that early labor will be coming in a few days, fetal lung maturity can be accelerated over a several day period by administering drugs such as betamethasone.
Unfortunately tocolytic drugs have side effects, such as maternal cardiac arrhythmias, and a number of these drugs also have side effects on the fetus as well. Thus these drugs are generally not given unless it is clear that there really are premature contractions.
Unfortunately, without instrumentation, patients often have difficulty in distinguishing between normal Braxton-Hicks contractions, the onset of abnormal uterine contractions such as preterm labor. As a result, in order to better detect preterm labor and other abnormal uterine contractions, in the early 1990's, various types of uterine contraction monitors, often called tocodynamometer devices, or Home Uterine Activity Monitors (HUAM), were introduced to the market.
These early HUAM devices were rather cumbersome however. The standard method of use was to instruct the patient to put the HUAM device on for an hour, collect data, then remove the HUAM device, connect the device to a telephone and transmit the data to a center on a twice daily basis.
After an initial burst of enthusiasm regarding the utility of HUAM, work since then has tended to discourage this approach. In 2001, the American College of Obstetrics and Gynecology published a position statement that cast doubt on the efficacy of these devices, and other studies since then have also been negative. At present, most major medical insurance carriers do not provide coverage for HUAM devices.